Measuring rheological properties of fluids for optimum maintenance and optimum wellbore hydraulic management is one of the most important tasks during drilling and other downhole operations. This task is conducted by viscosity measurements that express a relationship between shear stress and shear rate. In drilling practice, such measurements are carried out at the rig site using test protocols and equipment as standardized by the American Petroleum Institute (API), such as API standards 13-B1, 13-B2, 13C and 13D.
Currently, the rheology determination is carried out with simplistic equipment at atmospheric pressure and standardized temperatures at the surface. The obtained rheology measurements therefore do not properly reflect the actual well conditions experienced by the fluid within the wellbore. Furthermore, measurements are not performed in real time and are conducted depending on the availability of the mud engineer. Inaccurate measurements of the rheological properties can possibly lead to miscalculated predictions of annular frictional pressure drops and Equivalent Circulating Density (ECD).
These rheological parameters are even more crucial during offshore drilling operations where a correct calculation of the ECD is vital. During offshore drilling operations the “mud window,” i.e. the difference between the fracture gradient and the pore pressure (or the mud pressure required to prevent shear failure at the wellbore wall, whichever of the two is higher), tends to be very narrow. Exceeding the boundaries of the mud window usually results in significant well trouble (e.g., well control incidents, lost circulation, borehole instability, stuck pipe, etc.) and associated trouble time and recovery costs. The methods and systems herein address these and other needs.